Damn motor running rich...sometimes

Hello,

So, for the last few months, my rig has been intermitantly running rich and feeling sluggish. It seems that if I start my rig before around 8:30 or 9:00 in the morning, it will run rich all day regardless of starting and stopping. If I start out later, everything runs fine. I've replaced plugs and wires and O2 sensors, but nothing seems to help. On a recent trip of about 160 miles, I got 14 mpg going one way with it running crappy and 20 mpg the other with it running fine. What the hell? Warming the engine up doesn't seem to help, neither does better gas? Even at correct engine temp., it doesn't run right. It either runs good from the moment I turn the key or it doesn't. Somebody help me please.

She needs coffee to get going in the morning? MAP sensor maybe. It detects atmospheric pressure if I remember right and adjusts the mixture accordingly, but I may be wrong.

Check your Coolant Temperature Sensor (various location for 4 & 6 cyl models and years). My MJ ran rich and bogged out my engine, crappy mileage, etc....

Locations: 4cyl, back drivers side corner of the intake manifold
6cyls...2 possible locations: on thermostat housing (newer models) or for older models, near front dottom drivers side of block.

Description: brass plug with 2 black wires coming out of it into a 2 prong conector.

The CTS tells the computer if the coolant is hot or cool so the computer can adjust the fuel / air mixture accordingly. On my sensor, the two wires had the coating stripped right near the plug where they twisted around each other...I'm sure they were grounding out signal or something. Since I replaced that sensor....all has been well.... well, except for the slave cylinder blowing.....